Sir Donough O'Brien, 1st Baronet of Leameneh (1642 – 17 November 1717) was an Irish politician and baronet. He was the son of Conor O'Brien of Leamanah and Máire Rua McMahon. He was the first member of his family to conform to the established church. He was an astute man who avoided declaring for either James II or William III. He was considered by his neighbours, ten years after the surrender of Limerick, as the richest commoner in Ireland. His eldest son Lucius pre-deceased him and he was succeeded in his baronetcy by his grandson Edward O'Brien.